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Biomedical subjects

F M Perez

Publications and source records attributed to F M Perez.

At least 19 recordsLinked to original sources
PubMed2005

Expression of the receptor of advanced glycation end products in gingival tissues of type 2 diabetes patients with chronic periodontal disease: a study utilizing immunohistochemistry and RT-PCR.

OBJECTIVES: Relationship between diabetes and periodontal disease is well established. It has been shown that advanced glycation end-products (AGEs) might exert noxious effects on gingival tissues through its receptor. Evidence for the role of receptors of AGE (RAGE) in periodontal disease was verified in a murine model for diabetes. However, the presence of RAGE in human gingival tissues has not been demonstrated previously. In this study we demonstrate the presence of RAGE in human periodontium in patients with chronic periodontitis with and without type 2 diabetes. MATERIAL AND METHODS: Gingival biopsies from eight patients with both type 2 diabetes and chronic periodontitis and 14 healthy control subjects with chronic periodontitis were immunohistochemically stained for RAGE. Five samples from the study groups and four controls were subjected to reverse transcriptase coupled to polymerase chain reaction (RT-PCR) for quantitative determination of mRNA for RAGE. RESULTS: On immunohistochemistry, positive staining for RAGE was seen in the endothelium and the basal and spinous layer of the inflamed gingival epithelium in both type 2 diabetes and non-diabetes tissue with no statistically significant difference between both groups. RT-PCR, however, showed a 50% increase in mRNA for RAGE in the gingiva of diabetic patients when compared with controls (p<0.05). CONCLUSIONS: Although there was no change in the staining intensity for RAGE between both groups, the increase in the mRNA for RAGE in the type 2 diabetes gingival epithelium may indicate a possible involvement of this receptor in the periodontal destruction in type 2 diabetes.

Chronic Disease↗
PubMed2004

Receptor of advanced glycation end product (RAGE) expression in the minor salivary glands of patients with Sjögren's syndrome: a preliminary study.

OBJECTIVE: Receptor for advanced glycation end product (RAGE) is a cell-surface receptor with ligands capable of inducing proinflammatory responses in autoimmunity. We investigated the immunohistochemical expression and immunoblotting of RAGE in labial salivary glands from Sjögren's syndrome (SS) patients. MATERIAL AND METHODS: Ten minor salivary glands from SS and 15 from normal salivary tissue adjacent to mucocele were stained immunohistochemically using an antibody to RAGE. Immunoblotting was performed on four SS biopsies and four controls from normal gland. RESULTS: Immunohistochemistry showed all sections positive for RAGE. The SS sections did not statistically differ from controls. In immunoblotting, SS samples expressed approximately 100% more RAGE than controls [probability (p)<0.03, Student's t-test]. CONCLUSIONS: RAGE is present in the labial salivary glands of both normal and SS patients, with preliminary data suggesting over-expression in SS tissues. The role of RAGE in the pathogenesis of SS has yet to be determined.

Aged↗
PubMed2001

In vivo control of NMDA receptor transcript level in motoneurons by viral transduction of a short antisense gene.

Glutamate receptors play critical roles in normal and pathological processes. We developed an antisense gene delivery strategy to modulate the NMDA type of glutamate receptor. Using transient transfection in vitro and viral mediated gene transfer in vitro and in vivo, the effect of expression of an antisense gene fragment (60 bp) of the NR1 subunit was tested. Immunoblot analysis showed an antisense-concentration-dependent reduction in the NR1 subunit upon transient co-transfection of a plasmid expressing a sense NR1 gene and a plasmid expressing the antisense fragment into COS-7 cells. After recombination into an adenoviral vector, this antisense fragment reduced the amount of endogenous NR1 protein in PC12 cells. Finally, direct intraparenchymal injection of the viral vector into rat spinal cord resulted in diminished NR1 in motor neurons. Our results demonstrate the efficacy of this approach, which combines antisense with viral gene delivery to control the expression of specific genes in vivo. This approach may also be useful in reducing excitatory neurotransmission in vivo, with implications for the treatment of spinal disorders such as amyotrophic lateral sclerosis or chronic pain.

Adenoviridae↗
PubMed2001

Renal mRNA response to reduced perfusion pressure conserved despite denervation in mature ovine fetuses.

We hypothesized that renal denervation in mature ovine fetuses reduces renin mRNA response to 24 h of reduced renal perfusion pressure (RPP). Seven occluder (O) (132.4 +/- 1.2 days gestation) and six control (C) (131.5 +/- 1.2 days gestation) fetuses underwent left renal denervation. Postoperatively, O fetuses experienced 24 h of reduced RPP by suprarenal aortic occlusion. Femoral arterial blood pressure (FAB) and plasma active renin (pARC) and prorenin (pPRC) concentrations were obtained hourly for 6 h and at h 23 and 24. Renin mRNA was measured by RNase protection assay. We quantitated renin containing glomeruli by immunocytochemistry. Variables were compared by ANOVA. Mean O group FAB reduction from baseline was -6.60 +/- 0.41 mmHg. pARC and pPRC increased with occlusion, renal ARC and renal PRC did not increase with occlusion. No effect in renin mRNA or number of positive glomeruli was noted with denervation in the basal state; however, significant increases were noted in response to RPP irrespective of innervation status. In conclusion, 24 h or reduced RPP in mature ovine fetus increases renal renin mRNA and the immunocytochemical expression of renin. This response is conserved despite denervation.

Animals↗
PubMed1999

Leukemia inhibitory factor as an intrapituitary mediator of ACTH secretion.

In the normal anterior pituitary, intercellular interactions are important for the expression of hormones including adrenocorticotropin (ACTH). Leukemia inhibitory factor (LIF) is secreted by anterior pituitary cells and stimulates both basal and corticotropin-releasing hormone (CRH)-stimulated ACTH secretion in AtT20 cells. To determine the effects of LIF on normal pituitary cells, we measured the effects of LIF and an immunoneutralizing antiserum against LIF on ACTH secretion by cultured sheep anterior pituitary cells. In intact populations of anterior pituitary cells, LIF (10 nM) stimulated ACTH secretion (from 0.30 +/- 0.06 to 0.77 +/- 0.01 ng/well per 3 h) and antiserum to LIF (by itself) had no effect (0.29 +/- 0.05 ng/well per 3 h). In marked contrast, following pharmacological elimination of CRH-target cells, a condition known to disinhibit ACTH secretion, basal ACTH secretion was elevated (0.74 +/- 0.13 ng/well per 3 h); LIF produced no further stimulation (0.73 +/- 0.22 ng/well per 3 h) but immunoneutralization of LIF significantly reduced secretion to 0.50 +/- 0.10 ng/well per 3 h. Medium, conditioned by exposure to CRH-target-depleted cultures of anterior pituitary cells, increased net ACTH secretion (from 0.29 +/- 0.03 to 6.54 +/- 0.71 ng/well per 3 h), when added as a challenge to naive, cultured anterior pituitary cells. Inclusion of antiserum to LIF significantly attenuated (5.29 +/- 0.62 ng/well per 3 h) this response. The presence in and secretion of LIF by normal individual pituitary cells was detected using immunocytochemical methods. Seven to 8% of all cells stained positively for LIF, with 66 +/- 11% of those secreting detectable amounts of LIF under unstimulated conditions. LIF colocalized with TSH and LH in pituitary cells. Taken together, these data suggest that LIF can stimulate ACTH secretion by normal anterior pituitary cells, and potentially plays a role as an intrapituitary stimulator of ACTH secretion under certain conditions.

Adrenocorticotropic Hormone↗
PubMed1997

Growth hormone secretion and synthesis are depressed in obesity-susceptible compared with obesity-resistant rats.

Human obesity is characterized by a low basal growth hormone (GH) concentration and a blunted response to GH secretagogues. The aim of this experiment was to determine whether a perturbation in GH synthesis or secretion occurs in rats that develop obesity only in response to a dietary fat challenge. Female Sprague-Dawley rats were fed a purified 32.5% fat diet ad libitum for 21 weeks. Approximately half of the rats fed this diet developed obesity (obesity-susceptible) while the others remained lean (obesity-resistant) compared with chow-fed (control) animals. Pituitary glands obtained from all three groups were enzymatically dissociated, and somatotrope response to GH secretagogues and inhibitors was determined in vitro. Plasma GH concentrations were decreased in obesity-susceptible rats compared with obesity-resistant rats, and in vitro GH secretory response was blunted in cells obtained from the pituitary glands of obese compared with lean rats. In addition, pituitary GH content was reduced in obese versus lean rats even though the proportion of somatotropes in the two groups did not differ. Since the changes in GH concentration in this dietary obese rat model parallel those found in human obesity, this model may be useful in determining the relationship between GH and obesity.

Animals↗
PubMed1997

Developmental changes in ovine corticotrophs in vitro.

We recently reported that fetal sheep corticotrophs (ACTH-producing cells) at 108 +/- 5 d (days) of gestation are relatively more responsive to CRH than to AVP, whereas those at 139 +/- 0 d (term = 145 d) and in the adult are more responsive to AVP. To further characterize these developmental changes, we used immunocytochemical, RIA, and cell immunoblotting techniques to examine populations of corticotrophs and individual cells. Immunocytochemical studies revealed that corticotroph frequency decreased from 22 +/- 1% of all pituitary cells at 100 d of gestation to 14 +/- 1% at 135 d and 9 +/- 0% in the adult. RIA measurements of ACTH secretion by cell populations showed that the response of corticotrophs to CRH diminished, whereas that to AVP increased during gestation and into adulthood. Cell blot analysis of individual corticotrophs identified two types of secretory responses (increases in the number of secreting cells and average amount of ACTH released per cell) to CRH or AVP that changed during fetal development. At 100 d of gestation, CRH increased the proportion of secreting cells from 65 +/- 3% (no test agent) to approximately 90%; AVP exerted a negligible effect on the relative abundance of secreting cells. At 120 d of gestation, both secretagogues, alone or in combination, increased the proportion of secreting corticotrophs from 49 +/- 6% to about 85%. At 135 d of gestation and in the adult, AVP, alone or in combination with CRH, increased secreting corticotrophs from about 53 +/- 6% to about 80%. CRH alone exerted a nominal effect on the proportion of secreting cells. Additional analyses showed that, at 100 or 120 d of gestation, the average amount of ACTH secreted by individual corticotrophs did not change in response to CRH or AVP. However, near term and into adulthood, the average quantity of ACTH released from individual cells increased in response to these agents. Our findings suggest that maturational changes in fetal corticotrophs dictate whether their secretory response to CRH or AVP results from an increase in the proportion of cells secreting ACTH and (or) an increase in the average amount of hormone secreted by individual cells.

Adrenocorticotropic Hormone↗
PubMed1996

Quantification and localization of N-acetyl-beta-D-hexosaminidase in the adult rat testis and epididymis.

An affinity-purified polyclonal antibody against N-acetyl-beta-D-hexosaminidase (EC 3.2.1.52) from adult rat epididymis was used to develop an ELISA, to localize tissue antigen by immunocytochemistry, and to identify isoforms of the enzyme by Western blot analysis. While peak activity level was measured in the corpus region of the epididymis, the quantity of soluble enzyme protein was highest in the caput region. Luminal caput sperm were intensely immunopositive, whereas epithelial cells were weakly stained. The enzyme was localized to epithelial and sperm cells of the corpus and caudal regions. In the testis, the enzyme was restricted primarily to lymphatic spaces. Testicular cells were unreactive, but spermatids were weakly stained. Western blot analysis revealed three prominent immune-reactive protein variants of approximately 63 kDa, approximately 55 kDa, and approximately 31 kDa. The approximately 31-kDa immune-reactive protein variant was reduced by > 84% in the caput epididymis compared to the cauda and corpus regions. These data suggest that regional differences in N-acetyl-beta-D-hexosaminidase activity in the rat epididymis may be due to differences in cellular synthesis and/or posttranslational processing of the enzyme.

Amino Acid Sequence↗
PubMed1996

Balint's syndrome arising from bilateral posterior cortical atrophy or infarction: rehabilitation strategies and their limitation.

Balint's syndrome is characterized by faulty visual scanning, dysmetria secondary to a visual perceptual deficit, and an inability to recognize more than one object at a time. We report three cases of Balint's syndrome and the individualized rehabilitation they received. One patient developed symptoms of Balint's syndrome caused by bilateral occipitoparietal infarcts. In the two other cases the symptoms arose secondary to posterior cortical atrophy, a slowly progressive dementia with alexia and agraphia. All three patients initially responded to a multicontext treatment approach with intensive verbal cueing and organizational strategies with subsequent improvement in visual recognition, reaching and scanning. Continued deterioration from posterior cortical atrophy or a second infarction resulted in worsening dementia in two patients. Cognitive remediation was required as visual perceptual rehabilitation became ineffective. Clinicians should be familiar with Balint's syndrome and its various aetiologies. Lack of awareness of this syndrome may lead to a misdiagnosis and resulting inappropriate or inadequate treatment.

Agnosia↗
PubMed1995

Anterior pituitary cells: getting to know their neighbors.

We review in this article recent findings on the effects of cell proximity (nearness to each other) on anterior pituitary cell function in vitro. Important cellular processes, including protein synthesis, basal hormone release, response to hypothalamic regulatory factors and signal transduction can change as a function of the distance between adjacent cells. These findings, together with a growing body of evidence on intrapituitary intercellular interactions, form a basis for proposing a model of anterior pituitary cell regulation. In this scheme extrapituitary, intracellular and intercellular signaling pathways all contribute and interact to control secretory processes in cells.

Animals↗
PubMed1993

Immunocytochemical studies of chicken somatotrophs and somatotroph granules before and after hatching.

Immunocytochemical methods were used to gain information about the embryonic development of chicken somatotrophs before and after hatching. To localize growth hormone, anterior pituitary sections were incubated with growth-hormone antibody, and then an indirect peroxidase method was used for light microscopy and an immunogold method for electron microscopy. The earliest evidence of embryonic somatotrophs was seen at 12 days. At this stage somatotrophs were sparse (0.2% of parenchymal cells) and their granules were pleomorphic with elongated ovoid and lozenge shapes predominating. Few of the immunogold-labeled somatotroph granules of the embryo were spherical until 15 days after fertilization. At 18 days, most of the granules were spherical (their shape in the adult chicken). During the six days between the 15-day-old embryo and the 1-day-old chick, the number of gold particles per granule section approximately doubled suggesting an increase in growth hormone content of the granules. This rise was the result of increases in the size of the granule sections and in the concentration of gold particles in the sections. During the embryonic period of 12-20 days, somatotrophs were not more than 3.6% of the anterior pituitary cell population. During the following two days, between the 20-day-old embryo and the 1-day-old chick, the percentage of somatotrophs in the pituitary parenchymal cell population rose rapidly from 3.6% to 20.7% and then increased slowly to 24.6% during the period of 1-5 days after hatching.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Identification of novel RNA-binding proteins that interact in the coding region of protein D sense RNA in vitro.

Ultraviolet (UV)-cross-linking and sodium dodecyl sulfate(SDS) polyacrylamide gel electrophoretic (PAGE) analysis were used to identify proteins of nuclear and cytosolic (S100) origin that specifically bind to an in vitro transcribed mRNA sequence for protein D. The coding region of the protein D cDNA was subcloned, in vitro transcribed to [32P]RNA, and incubated with nuclear and cytosolic extracts of enzymatically dispersed epididymal cells. As revealed by UV-cross-linking and SDS-PAGE analysis, two proteins exhibiting a molecular weight mass of approximately 2.5 and approximately 35 Kd that specifically recognize and bind to the in vitro transcribed mRNA sequence for protein D. Our findings suggest that the regulation of protein D gene expression in the rat epididymis may involve novel RNA-binding proteins.

Animals↗
PubMed1992

Purification and characterization of N-acetyl-beta-D-hexosaminidase in different anatomical regions of the adult rat epididymis.

The purpose of the present study was to purify and kinetically characterize N-acetyl-beta-D-hexosaminidases A and B (EC 3.2.1.52) from the caput, corpus and caudal regions of the adult rat epididymis. The molecular mass of the purified native enzyme was approximately 250,000 and approximately 223,000 daltons for the A and B isozymes, with a subunit molecular mass of approximately 63,000 and approximately 56,000 daltons, as determined by size exclusion chromatography and gel electrophoresis under reducing conditions. The apparent Michaelis-Menten constant and maximum velocity values were 0.60, 1.55 and 0.68 mM and 0.54, 3.20 and 2.30 microM/min./mg protein for the enzyme purified from the caput, corpus and caudal regions, respectively. These values were determined by using p-nitrophenyl-N-acetyl-beta-D-glucosaminide as the substrate. These data suggest that the enzyme may be more active in the corpus region of the epididymis than in the caput and caudal regions.

Animals↗
PubMed1990

Stimulation of chicken growth hormone release by phorbol esters.

Synergism between thyrotropin-releasing hormone (TRH) and human pancreatic growth hormone-releasing factor (hpGRF) has been shown in a primary (48 hr) culture of chicken adenohypophyseal cells established in this laboratory. The purpose of the present study was to determine if phorbol esters acting alone or in concert with TRH or hpGRF affect chicken GH release. Collagenase-dissociated chicken adenohypophyseal cells were treated (2 hr) with combinations of TRH, hpGRF, phorbol esters (activators of protein kinase C; PKC), and pharmacologic agents that increase cAMP. Phorbol myristate acetate (PMA) or phorbol dibutyrate (PDBu) alone stimulated GH release in a dose-dependent manner; either phorbol ester (10(-6) M) increased GH release from 100 to 390% over the value obtained in the absence of test agents (control). Similarly, hpGRF (10(-9) M), 8 Br-cAMP (10(-3) M), forskolin (10(-6) M), or isobutylmethylxanthine (IBMX, 10(-3) M) alone elevated GH release by at least 60% over the control value. The combined effects of phorbol esters (either PMA or PDBu) and hpGRF, 8 Br-cAMP, or forskolin on GH release were additive. Only one combination, phorbol esters with IBMX, exerted synergistic effects on GH release. No synergy was shown between TRH (1.3 x 10(-9) M) and either phorbol ester. These findings are the first to implicate PKC in chicken GH release in vitro. In addition, these studies, together with previous results, suggest that TRH and hpGRF synergy occurs via a pathway that arises prior to activation of PKC.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Influence of catecholamines, prostaglandins and thyroid hormones on growth hormone secretion by chicken pituitary cells in vitro.

In young chickens plasma concentrations of growth hormone (GH) are depressed by prostaglandins (PG) E1 and E2, epinephrine, norepinephrine, alpha 2 and beta agonists or thyroid hormones. A primary culture of chicken adenohypophyseal cells was used to examine the direct effects of these agents at the level of the pituitary as evaluated by GH release in the presence and absence of growth hormone releasing factor (GRF). Following collagenase dispersion and culture (preincubation, 48 hr) cells were exposed (incubation, 2 hr) to test agents, except for thyroid hormones which were added during the preincubation, and incubation period. Growth hormone release was increased (P less than .05) in the presence of PGE1 (10(-8)M by 34%; 10(-7)M by 54%), PGE2 (10(-8)M by 29%; 10(-7)M by 29%), PGF2 alpha (10(-8)M by 28%), and the beta agonist isoproterenol (10(-7)M by 46%). Basal GH release from chicken pituitary cells was not affected by dopamine, norepinephrine, epinephrine, thyroxine (T4), triiodothyronine (T3), or alpha adrenergic agonists. Growth hormone releasing factor stimulated GH release was not affected by the presence of prostaglandins E1, E2 or F2 alpha in the incubation media. However, GRF stimulated GH release was reduced by high doses of catecholamines: dopamine (10(-6)M by 34%), norepinephrine (10(-6)M by 74%), epinephrine (10(-8)M by 47%; 10(-7)M by 41%; 10(-6)M by 89%), and by the alpha 1 adrenergic agonist, phenylephrine (10(-7)M by 52%), the alpha 2 agonist, clonidine (10(-8)M by 34%; 10(-7)M by 83%) and the beta agonist, isoproterenol (10(-7)M by 64%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A new tissue-slicing method for the study of function and position of somatotrophs contained within the male rat pituitary gland.

A tissue-slicing method has been developed for obtaining quantitative information relative to the function and distribution of somatotrophs in the individual pituitary of the male rat. The adenohypophysis was cut along midtransverse, coronal, and sagittal planes, dividing the gland into eight distinct slices. Basal (unstimulated) GH release was measured from sections placed in gyrotory incubation for three consecutive periods (20 min each). Response to rat hypothalamic GH-releasing hormone (rhGHRH) was studied in slices placed in perifusion and in dispersed cells placed in static incubation. Tissues and cells were analyzed by light and electron microscopy and flow cytometry. Cells retained good morphological integrity and viability (greater than 85%) after incubation (1 h) or perifusion (5 h). Somatotrophs were evenly distributed sagittally and rostrocaudally, but were unevenly distributed dorsoventrally; mean values for dorsal and ventral sections were 45.3 +/- 2.5% and 38.9 +/- 1.9%, respectively. Differential basal GH release was observed after the first gyrotory incubation period; values differed by as much as 3-fold. These differences became less apparent with subsequent incubations. Pituitary slices in perifusion showed a differential response to rhGHRH. For some sections GH release increased up to 2-fold; in other sections the response was either negligible or absent. Dissociated cells from sections also showed differential response to rhGHRH; increases ranged from 160-250% above unstimulated values. These studies demonstrate that tissue slicing is a useful method for investigating pituitary cell function in vitro. The correlation between function and position suggests that heterogeneity of somatotrophs is related in part to their location in the gland.

Animals↗
PubMed1989

Growth hormone release from chicken anterior pituitary cells in primary culture: TRH and hpGRF synergy, protein synthesis, and cyclic adenosine 3'5'-monophosphate.

Our earlier work showed that the effects of thyrotropin-releasing hormone (TRH) and human pancreatic growth hormone-releasing factor (hpGRF) on growth hormone (GH) release are synergistic (greater than additive) in a primary culture of chicken adenohypophyseal cells. The purpose of the present studies was to investigate the possible participation of protein synthesis and cyclic adenosine 3'5'-monophosphate (cAMP) in GH release. Following culture (48 hr), cells were incubated for 2 hr with test agents. Cycloheximide (an inhibitor of protein synthesis) had no effect on basal (absence of test agent) GH release or hpGRF-induced GH release. However, cycloheximide abolished the synergy between TRH and hpGRF. Although neither TRH nor hpGRF alone stimulated GH production (intracellular GH plus GH release) during a 2-hr incubation period, in combination these secretagogues increased total GH. These findings suggest that GH release from the chicken somatotroph under conditions of TRH and hpGRF synergy requires protein synthesis. In other studies, cells were exposed to agents inducing the formation of cAMP and either TRH or hpGRF. 8 Br-cAMP (10(-3) M), forskolin (10(-6) M), or isobutylmethylxanthine (IBMX; 10(-3) M) alone stimulated GH release to values between 30 and 50% over the basal value. The combined effects of each of these agents and TRH on GH release were synergistic. Similarly, IBMX and hpGRF exerted synergistic effects on GH release. In contrast, no synergy was shown between hpGRF and either 8 Br-cAMP or forskolin; their combined actions were less than additive.

1-Methyl-3-isobutylxanthine↗